In the United States, overweight (BMI > 25 but < 30 Kg/m2) and obesity (BMI > 30Kg/m2) are increasing at epidemic rates. A significant association exists between being overweight or obese and breast cancer recurrence and survival. However, evidence continues to accumulate indicating that achieving or maintaining a healthy weight for height (Body Mass Index, BMI, 18.5-25Kg/m2) is associated with a reduced risk for breast cancer and with a decrease in breast cancer associated mortality. Despite this, there is a lack of randomized controlled trials exploring this association and how the process of fat loss or being successful in actually reaching a healthy weight for height differentially affects biomarkers for cancer recurrence.